Cytokine-Induced Expression of Vascular Endothelial Growth Factor in Peritoneal Mesothelial Cells / 대한신장학회잡지

ABSTRACT

BACKGROUND: The mechanism of increased peritoneal permeability during peritonitis has not been clearly determined. We studied the changes in vascular endothelial growth factor (VEGF) levels in dialysate effluents during CAPD peritonitis, and VEGF expression in cultured peritoneal mesothelial cells (MCs) stimulated with IL-1 alpha, TNF alpha, and IFN gamma. METHODS: In 30 CAPD patients with peritonitis, dialysate effluents were serially collected at the time of diagnosis of peritonitis and when the peritonitis was recovered. Primarily cultured MCs were incubated with IL-1alpha or TNFalpha alone or in combination with INF gamma. VEGF level in dialysate effluent and MCs conditioned medium was measured by sandwich ELISA. VEGF mRNA expression was analyzed by Northern blotting. The activation of NFkappaB in response to IL-1alpha or TNFalpha was measured by electrophoretic mobility shift assay (EMSA). RESULTS: VEGF levels in dialysate effluent at the time of diagnosis of peritonitis were significantly higher (456+/-45 pg/mL) than those when the peritonitis was recovered (245+/-21 pg/mL)(p<0.00001). Both IL-1 alpha and TNFalpha stimulated VEGF production in MCs, and the stimulation was significant from 24 hours to 72 hours. INFgamma, in combination with IL-1 alpha or TNF alpha, significantly amplified IL-1 alpha - or TNF alpha - induced VEGF production. Pre-incubation of MCs with NF kappa B inhibitor, pyrrolidine dithiocarbamate, totally blocked IL-1 alpha - or TNF alpha-induced VEGF production. Northern blot analysis revealed that IL-1 alpha and TNF alpha stimulated VEGF mRNA expression in a dose dependent manner. The stimulation was peak at 4 hours. IL-1alpha and TNF alpha stimulated NFkappa B binding activity in MCs as early as at 15 minutes, with a peak activity at 1 hour, and p65 subunit was supershifted. CONCLUSION: Our results suggest that increased expression of VEGF in peritoneal mesothelial cells stimulated with proinflammatory cytokines, IL-1alpha, TNFalpha, and IFN gamma, plays a role in the increased peritoneal permeability during CAPD peritonitis.